Blitzer traveled to a NATO meeting in Brussels with Panetta and interviewed the defense secretary and Secretary of State Hillary Rodham Clinton.

Panetta said he is concerned about North Korea, Iran, Syria and the turmoil in the Middle East. Beyond that, he added, he also worries about threats posed by cyber war, weapons of mass destruction and rising powers. “All of those things are threats that the United States faces in today's world,” he said.

On Syria, Clinton said the U.S. goal is to see Bashir al-Assad’s government stop killing its own people.

“The goal right now is if the Assad regime were to say, ‘OK, we agree, we're going to do everything that [United Nations envoy] Kofi Annan asks us to do,’ that will be our focus -- not some future, maybe unlikely, outcome in terms of criminal accountability,” she said. “What I'm interested in is ‘Let’s stop the violence and let’s start the political transition.’”

The United States stands ready to do what the international community decides on Syria, she added.

The administration has taken a firm stand on North Korea and the provocative behavior of its new ruler Kim Jong Un, Panetta said. “We’re within an inch of war almost every day in that part of the world,” he said. “And you just have to be very careful about what we say and what we do.”

The U.S. alliance with South Korea is strong, Panetta said, and more than 28,000 U.S. service members are based in the country, providing a tangible example of U.S. commitment to peace in Northeast Asia.

Provocations such as North Korea’s recent failed rocket launch and threats of testing a nuclear weapon should stop, Panetta said. “The fact is it was provocative, and we have made it very clear to them that they should not take any additional, provocative actions,” he said.

The defense secretary stressed that this is not just a U.S. wish, but that the international community wants North Korea to end its provocations.